I, too, recently ran a dedicated 20A circuit to my listening room.
I used 12/3 (metal-clad) cable - essentially a 240v circuit (like Dan), split into to two 120v circuits, so I could power the system on the "quieter" one. (The stand-up A/C in the adjacent room gets the other circuit, only in the hot summer.) I used 12ga as I was loathe to deal with the 10ga wire for the 30A rating, though there is some thinking that the 10ga wire does help with instantaneous current demand even if you're not using particularly "high current" gear (see Shunyata's DTCD research). If you can, make sure you have no other "connections" on the circuit between the panel and the outlet(s), or that the connections are very tight and secure if you must have any connections, to allow the best instantaneous current transfer and lowest noise. (An "Ideal 61-164 Circuit Analyzer" can measure the transient current capability of the branch circuit, but it's ~$300 and I haven't convinced myself that I need one... yet.)
In your situation, doing what I (and Dan) did and running a 240v circuit split in two may allow you to put the sound system on one leg, and the computers and oil heater on the other, further reducing interactions, at least in the winter. (EDIT: I re-read and see that you're considering 2 circuits. I'd highly recommend that, and forget my suggestion of a 240 split in two; I just did it that way out of necessity.)
I used the Leviton "Heavy Duty Industrial" outlets available at Home Depot, and they provide a strong, tight grip on the plugs. I have not yet upgraded those, and if I do, it will likely be the Shunyata/Hubbel SR-Z1 outlets, or the CopperCONNs if I'm feeling spendy.
For me, the upgrade was a sonic improvement, and subsequent refinements (cables, conditioner(s)) have been additionally fruitful.